A ternary string is a sequence of 0s, 1s, and 2s. How many ternary strings of length 15 are there? How many of those strings contain exactly seven 0s, five 1s, and three 2s? How many ternary strings of length 15 have even weight, i.e., contain an even number of 1s?
(1) there are 3^(15) of length 15. The second two parts I'm not sure about I know for a binary string (n choose w) will give you the number of strings of length n and weight w but I'm not sure how to apply this to ternary strings. Any help would be appreciated